<template>
  <ul class="list-none px-0" v-if="items.length">
    <li v-for="(item, i) in items" :key="i">
      <SidebarGroup
        v-if="item.type === 'group'"
        :item="item"
        :open="i === openGroupIndex"
        :collapsable="item.collapsable || item.collapsible"
        :depth="depth"
        @toggle="toggleGroup(i)"
      />
      <SidebarLink v-else :sidebarDepth="sidebarDepth" :item="item" />
    </li>
  </ul>
</template>

<script>
import SidebarGroup from '@theme/components/SidebarGroup.vue';
import SidebarLink from '@theme/components/SidebarLink.vue';
import { isActive } from '../util';

export default {
  name: 'SidebarLinks',
  components: { SidebarGroup, SidebarLink },
  props: [
    'items',
    'depth', // depth of current sidebar links
    'sidebarDepth', // depth of headers to be extracted
  ],
  data() {
    return {
      openGroupIndex: 0,
    };
  },
  created() {
    this.refreshIndex();
  },
  watch: {
    $route() {
      this.refreshIndex();
    },
  },
  methods: {
    refreshIndex() {
      const index = resolveOpenGroupIndex(this.$route, this.items);
      if (index > -1) {
        this.openGroupIndex = index;
      }
    },
    toggleGroup(index) {
      this.openGroupIndex = index === this.openGroupIndex ? -1 : index;
    },
    isActive(page) {
      return isActive(this.$route, page.regularPath);
    },
  },
};

function resolveOpenGroupIndex(route, items) {
  for (let i = 0; i < items.length; i++) {
    const item = items[i];
    if (descendantIsActive(route, item)) {
      return i;
    }
  }
  return -1;
}

function descendantIsActive(route, item) {
  if (item.type === 'group') {
    return item.children.some(child => {
      if (child.type === 'group') {
        return descendantIsActive(route, child);
      } else {
        return child.type === 'page' && isActive(route, child.path);
      }
    });
  }
  return false;
}
</script>
